Create independent block attempts and cancel channel downloads safely

src/media_delivery/media_delivery.c

@@ -1384,40 +1384,16 @@ void media_delivery_cancel_channel(struct UTUN_INSTANCE* inst, uint64_t group_id
         if (stream->group_id == group_id) stream_free(stream);
         stream = next;
     }
-    struct relay_fwd_ctx* forward = md->forwards;
-    while (forward) {
-        struct relay_fwd_ctx* next = forward->next;
-        if (forward->group_id == group_id) relay_fwd_free(forward);
-        forward = next;
-    }
-
-    /* 1. собрать media_id активных загрузок этого канала и отменить их */
-    uint8_t media_ids[MEDIA_MAX_DOWNLOADS][16];
+    /* Callback отмены может изменить остальные загрузки: каждый раз ищем следующую заново. */
     int nm = 0;
-    if (md->downloads) {
-        struct ll_entry* de = md->downloads->head;
-        while (de) {
-            struct media_download* dl = (struct media_download*)de->data;
-            struct ll_entry* next = de->next;
-            if (dl->group_id == group_id) {
-                if (nm < MEDIA_MAX_DOWNLOADS) memcpy(media_ids[nm++], dl->media_id, 16);
-                media_download_cancel(inst, dl->media_id, NULL, 0);
-            }
-            de = next;
-        }
-    }
-
-    /* 2. удалить relay-контексты этих media (остаются после отмены загрузки) */
-    for (int i = 0; i < nm; i++) {
-        if (!md->relay_blocks) break;
-        struct ll_entry* re = md->relay_blocks->head;
-        while (re) {
-            struct relay_block_ctx* rc = (struct relay_block_ctx*)re->data;
-            struct ll_entry* next = re->next;
-            if (memcmp(rc->media_id, media_ids[i], 16) == 0)
-                md_relay_remove(md, rc->block_id);
-            re = next;
+    for (;;) {
+        struct media_download* found = NULL;
+        for (struct ll_entry* e = md->downloads ? md->downloads->head : NULL; e; e = e->next) {
+            struct media_download* dl = (struct media_download*)e->data;
+            if (dl->group_id == group_id) { found = dl; break; }
         }
+        if (!found) break;
+        media_download_cancel(inst, found->media_id, NULL, 0); nm++;
     }
 
     /* 3. удалить super_peers этой группы */

src/media_delivery/media_download.c

@@ -13,6 +13,7 @@
 #include "../routing_layer/etcp_router.h"
 #include "../routing_layer/conn_mgr.h"
 #include "../routing_layer/topo_group.h"
+#include "../routing_layer/topo_node_sqlite.h"
 #include "../transport_layer/etcp_api.h"
 #include "../transport_layer/secure_channel.h"
 #include "../lib/debug_config.h"
@@ -24,6 +25,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <openssl/evp.h>
+#include <openssl/rand.h>
 
 #define MDL_ID "media_download"
 
@@ -55,11 +57,14 @@ static int md_dl_block_inflight(const struct media_download_block* block) {
 }
 
 static int md_dl_reset_block_file(struct media_download* dl, int bi) {
-    char tmp[2048];
-    snprintf(tmp, sizeof(tmp), "%s.chunk_%d", dl->dest_path, bi);
-    FILE* f = fopen(tmp, "wb");
-    if (f && !fclose(f)) return 0;
-    DEBUG_ERROR(DEBUG_CATEGORY_MEDIA, "%s: cannot reset block file %s: %s", MDL_ID, tmp, strerror(errno)); return -1;
+    struct media_download_block* b = &dl->blocks[bi];
+    if (b->source) { md_block_abort(b->source); md_block_release(b->source); b->source = NULL; }
+    if (RAND_bytes(b->transfer_id, sizeof(b->transfer_id)) != 1) {
+        DEBUG_ERROR(DEBUG_CATEGORY_MEDIA, "%s: transfer UUID generation failed block=%d", MDL_ID, bi); return -1;
+    }
+    b->source = md_block_create(&dl->inst->md, dl->group_id, dl->media_id, b->block_id,
+                                (uint32_t)bi, b->expected_size, dl->dest_path);
+    return b->source ? 0 : -1;
 }
 
 static struct media_download_peer* md_dl_get_peer(struct media_download* dl, uint64_t node_id) {
@@ -130,11 +135,10 @@ static int md_dl_send_block_req(struct UTUN_INSTANCE* inst, uint64_t dst, struct
     struct media_pkt_block_req req;
     memset(&req, 0, sizeof(req));
     req.subcmd = MEDIA_SUBCMD_BLOCK_REQ;
-    req.group_id = dl->group_id;
     memcpy(req.media_id, dl->media_id, 16);
     memcpy(req.block_id, dl->blocks[bi].block_id, 16);
+    memcpy(req.transfer_id, dl->blocks[bi].transfer_id, 16);
     req.chunk = (uint32_t)bi;
-    req.offset = 0;
 
     DEBUG_INFO(DEBUG_CATEGORY_MEDIA, "%s: BLOCK_REQ to 0x%016llx blk=%d/%d block_id=%02x%02x%02x%02x...",
                MDL_ID, (unsigned long long)dst, bi, dl->num_blocks,